Friday, 10 June 2016

Real 1DXm2 vs 1DX high ISO performance comparison

Some time ago DPR added 1DXm2 to their comparison chart.There 1DXm2 high ISO performance looked slightly better than 1DX. The only one strange thing was there that 1DXm2 shots were brighter than 1DX shots.Actually,
it was required in LR to move exposure slider about 0.5 stop down for
1DXm2 and raise it about 0.2 stop up for 1DX to make them equal in
brightness and the same histogram distributions.Some people were
telling that this is OK and this is just due to difference in analog
gain setting in different cameras for different ISOs.

Therefore, when I got my 1DXm2 few days back I did some tests to check different things including high ISO performance. For
1DXm2 my primary interest was better AF, especially in in dim light
conditions and slightly better ISO, which was noticeable in DPR test.
My tests were done in dim light conditions using the same EF70-200
F/2.8L IS USM II lens fixed on the heavy and sturdy tripod. Once test
done with first camera then it was detached from the lens and then other
one was attached to the same lens on tripod. So all test conditions
were identical for both 1DX and 1DXmII.

So first set of tests
discovered that for the same ISO settings and same aperture value 1DX
and 1DXm2 were using different exposure values, 1DXm2 was doing
approximately from 1.3 to 1.67 longer exposure compared to 1DX and this
difference was increasing at higher ISOs.

As result I had to do
exposure corrections described above for both 1DXm2 and 1Dx to bring
shots from them to the same brightness level.For me this means that
1DXm2 high ISO comparison test presented so far at different sources
using the same ISO settings and auto-exposure are not correct source for
comparison ISO performance and this would be cheating people around the
world. Definitely, with the same ISO settings camera that captured 1.7
more light by its sensor will have less noise in output RAW files.On
the other hand, this simply means that exposure meter on 1DXm2 does
better job compared to 1DX and it does not underexpose shots, as it was
the case for many Canon cameras including previous 1D series bodies.
With 1Dxm2 shot histogram is now about 0.7 stops closer to the right.But
proper High ISO comparison test must be done using the same exposure
time and same aperture value for given ISO at both compared cameras and
only such test could give proper results.

Therefore, I did
another set of test shots, first with 1DX with auto exposure and then
for 1DXm2 in manual setting using exactly the same exposure and aperture
as for test shots with 1DX. This ensured that both sensors captured exactly the same amount of light for each ISO .As result, these sensor ISO performance test shots now could be directly compared.There
were four (4) test shots for each camera - aperture 4.0 for all shots,
ISO values 6400, 12800, 25600 and 51200 with shutter speeds 1/10, 1/20,
1/40, 1/80 respectively. So all test shots had absolutely the same amount of light captured by each camera sensor for each ISO settings.What I had at the end is something that I was expecting before but could not check that myself until I got my 1Dxm2.

As
I was suspecting comparison results were not a big surprise for me –
my old 1DX has slightly better high ISO performance compared to new
1DXm2.Here are attached snapshots done by Window snipping tool from
LR screen at 100% view - left side is 1DX, right side is 1DXm2. All
have the same LR default NR setting, luminous NR sliders set to zero. No
exposure corrections – both shot get exactly the same amount of light
captured by sensors. One real surprise for me was that all 1DX
shots are perfectly sharp while some 1DXm2 shorts are slightly blurred.
For both I was using one-shot AF mode with one center point surrounded
by 8 expansion point.Both were pointing at exactly the same are on
the target, as lens on tripod was not moved while changing camera body
attached to the lens. Shots was done using remote control and 2sec
self-timer. IS was switched OFF.This was kind of AF precision test in dim light condition.I
did not do yet AFMA for my lens on new 1DXm2 body and it could be
result of that, but that would be affecting all test shots for 1DXm2,
but some are more or less sharp and some not and all 1DX shots are
sharper than 1DXm2 shots.This is some kind of disappointment for me and I need to investigate that later.